Coupling pin for an electric dry-shaver

ABSTRACT

A sheet metal coupling pin for driving a rotatable cutter of a dry-shaver, which cutter is capable of limited tilting movement and is formed with a coupling slot, the coupling pin being formed with rounded portions the radii of curvature of which are in a given relationship with the length and the width of the slot.

United States Patent 11 1 Tietjens COUPLING PIN FOR AN ELECTRICDRY-SHAVER [75] Inventor: Eduard Willem Tietjens, Drachten,

Netherlands [73] Assignee: U.S. Philips Corporation, New

York, NY.

221 Filed: Nov. 29, 1973 211 Appl. No: 420,115

[30] Foreign Application Priority Data Dec. 22, 1972 Netherlands 7217486[52] [1.5. CI 30/43.6; 64/6 [51] Int. Cl B26b 19/14 [58] Field of Search30/42, 43.4-43.6;

THICKNESS-b- 1 1 June 24, 1975 [56] References Cited UNITED STATESPATENTS 3,078,571 2/1963 Timmerman 30/436 3,213,719 10/1965 Kloack M81/71 3,399,453 9/1968 Biesma 30/436 3,748,731 7/1973 Kuiken 30/436Primary Examiner-A1 Lawrence Smith Assistant ExaminerGary L. SmithAttorney, Agent, or FirmFrank R. Trifari 57] ABSTRACT A sheet metalcoupling pin for driving a rotatable cutter of a dryshaver, which cutteris capable of limited tilting movement and is formed with a couplingslot, the coupling pin being formed with rounded portions the radii ofcurvature of which are in a given relationship with the length and thewidth of the slot.

5 Claims, 5 Drawing Figures LENGTH PATENTEBJun 24 I975 SHEET 'fIII/IIIIJi &\

PATENTEDJuu24 m5 SHEET 3 -LEN THICKNESSH r-/7 WIDTH Fig.5

COUPLING PIN FOR AN ELECTRIC DRY-SHAVER BACKGROUND OF THE INVENTION Theinvention relates to a metal coupling pin for use in an electricdry-shaver having at least one shaving head capable of limited tiltingmovement. where a cut ter comprises a plurality of blades, and isadapted to be rotatably driven and co-operates with the shaving head. Acoupling member which is also adapted to be rotatably driven, is capableof limited tilting movement. at its end nearer the cutter carries thecoupling pin and thrusts the coupling pin into engagement with the cutter and hence the cutter into engagement with the shaving head underspring action. The cutter is formed with a coupling slot of rectangularcross-section having parallel walls into which the coupling pin engagesso as to cooperate with the shorter walls of the coupling slot by meansof portions having a curvature, the radius of which is substantiallyequal to one half of the width of the longer walls. and to co-operatewith the longer walls by means of portions having a curvature the radiusof which is substantially equal to one half of the width of the shorterwalls.

My co-pending Netherlands Pat. No. 6,810,708 and US. Pat. No. 3,748,731laid open to public inspection describes such a coupling pin. Animportant requirement is that during operation of the dry-shaver the cutter should always be in engagement with the associated shaving head,because otherwise a rocking movement of the cutter relative to the headis producedv This results in some of the hairs which project through theshear plate not being cut. This rocking movement. which is felt by theuser as a disagreeable vibration of the shaving head, is alsoresponsible for uneven wear of the shaving head, so that the incompleteengagement of the cutter with the shaving head is further aggravated.

The coupling pin described in said prior art US. Pat. No. 3,748,73lprovides satisfactory results, because there is a universal drivingrelationship between the cutter and the coupling pin. The coupling pinis a hardened steel component, the cylindrical lateral surfaces of whichhaving the said radii of curvature was formed by grinding. Such couplingpins are comparatively expensive, in particular because of the requiredgrinding operation which has to be performed with a comparatively highdegree of accuracy on a component which owing to its small size isdifficult to handle.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a coupling pin of the kind described at the beginning of thisspecification; the manufacture of such coupling pin based on therecognition that dry-shavers of the type in which the coupling pin is tobe used always have cutters which are driven in one direction only. canbe appreciably simpler, resulting in lower cost. This invention ischaracterized in that the coupling pin is made of steel sheet, and itsportions which cooperate with the longer walls of the coupling slotcomprise extensions of the required radius of curvature made bypressing. The coupling pin according to the invention can bemanufactured by stamping, which means a considerable simplification ofthe manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may bereadily carried into effect, reference will now be made by way ofexample to the accompanying drawings, in which FIG. I is a partialsectional view of an electric dryshaver,

FIG. 2 is an elevation sectional view of the coupling pin of FIG. Ishown 20 times actual size, which is mounted in the end of a couplingmember and cooperates with a cutter part shown in section,

FIG. 3 is a side elevation of the coupling member shown in FIG. 2,

FIG. 4 is a plan view of a coupling member arranged in a rectangularcoupling slot of a cutter in a position in which it is slightly rotatedabout its axis from a sub stantially parallel relationship with theslot, so that its extensions engage the longer walls of the slot, and

FIG. 5 is an elevation sectional view of the coupling pin and of part ofa cooperating cutter taken at right angles to the longer walls of thecoupling slot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG.I, there is shown a circular shaving head shear plate I. The head has anumber of slits 2 and is capable of limited tilting movement rela tiveto a frame plate 3 which is connected to the housing, not shown, of thedry-shaver. A cutter 4 which is adapted to be rotatably driven andcomprises six blades 5 cooperates with the shear plate I. A couplingmember 6, is rotatably driven. is capable of a limited tilting movement,and carries a coupling pin 7 at its end near the cutter. The couplingmember 6 has terminal part as the drive end of its coupling pin 7 thrustinto engagement with a stop member 30 of the cutter 4 by a compressionspring 8 mounted in a recess 9. As a result the cutter 4 is thrust intoengagement with the shear plate 1. The cutter 4 is formed with acoupling slot I0 of rectangular section, see in particular FIG. 4,having two pairs of parallel walls 11, I2 and I3. 14. The coupling pinengages in the slot I0 and cooperates with the shorter walls I1 and I2by means of portions 15 and 16 having a curvature the radius of which issubstantially equal to one half of the width of the longer walls 13 andI4, and cooperates with the said longer walls by means of portions 17and 18 having a curvature the radius of which is substantially equal toone half of the width of the shorter walls 11 and 12. These ears arealso bent out of the plane ofthe sheet material as indicated at 28, 29in FIG. 4, wherein the radius of the outer surface of the curvature ofeach of said ears 28, 29 is substantially equal to one-half the lengthof the short side 11 of the rectangular aperture. With these dimensionalparameters it is now feasible to manufacture this coupling pin from flatsheet metal which is cut to shape and then pressed into final shape.This is substantially cheaper than the final shape formed out of a solidblock or having same cast, The lower end of the coupling member 6 iswidened to form a flange 19 of square cross-section which fits in achamber 20 of corresponding crosssection formed in a gear-wheel 21. Thechamber 20 is closed by means ofa spring clip 22. On its other surfacethe gear-wheel 21 has a hub 23 in which a bore 24 is formed in whichfits a pin 25, the other end 26 of which is knurled and pressed into amounting plate 27. The gear-wheel 21 can be driven by a rotatingelectric motor via a transmission gear, not shown, the coupling member 6transmitting the rotary movement to the cutter 4.

I claim:

1. In a shaving head of a rotary dry shaver including a shear platetiltably mounted within a housing, a rotatably cutter positioned forengaging said shear plate. drive means for imparting rotary motion. acoupling member having a first part engaged and driven by said drivemeans and a drive end formed as a coupling pin for engaging and drivingsaid cutter. and spring means engaging and urging said coupling pinaxially against said cutter which is correspondingly urged axiallyagainst said shear plate the improvement in combination therewithwherein said cutter has defined therein a central, rectangular aperturedefining a pair of long side-walls and a pair of side-walls forreceiving said coupling pin, and said coupling pin is formed of sheetmaterial and comprises a shank having length and width in the plane ofthe sheet and thickness. and a drive end which is insertable axiallywithin said aperture and has a pair of ears which extend in the oppositedirections widthwise each bar having a rounded outer edge of radiussubstantially equal to one-half of the length of one of said long walls.each ear also curved out of the plane of said sheet about a lengthwiseaxis, with the outer surface of each ear having a radius about said axissubstantially equal to one-half the length of one of said shorter walls.

2. Apparatus according to claim 1 wherein said cutter further comprisesa stop member covering said aperture and situated intermediate the shearplate and coupling pin and wherein said drive end of the coupling pinhas a rounded terminal part which is urged axially into engagement withsaid stop member.

3. Apparatus according to claim 1 wherein said coupling pin is tiltablymounted relative to said housing.

4. Apparatus according to claim 1 wherein said coupling member iscylindrical with a central bore. and said coupling pin is a separateelement mounted for axial movement in said bore and said spring means issituated in said bore and urges said pin axially outward of the bore 5.Apparatus according to claim 1 wherein said cou pling pin comprisessheet metal.

1. In a shaving head of a rotary dry shaver including a shear platetiltably mounted within a housing, a rotatably cutter positioned forengaging said shear plate, drive means for imparting rotary motion, acoupling member having a first part engaged and driven by said drivemeans and a drive end formed as a coupling pin for engaging and drivingsaid cutter, and spring means engaGing and urging said coupling pinaxially against said cutter which is correspondingly urged axiallyagainst said shear plate, the improvement in combination therewithwherein said cutter has defined therein a central, rectangular aperturedefining a pair of long side-walls and a pair of side-walls forreceiving said coupling pin, and said coupling pin is formed of sheetmaterial and comprises a shank having length and width in the plane ofthe sheet and thickness, and a drive end which is insertable axiallywithin said aperture and has a pair of ears which extend in the oppositedirections widthwise, each bar having a rounded outer edge of radiussubstantially equal to onehalf of the length of one of said long walls,each ear also curved out of the plane of said sheet about a lengthwiseaxis, with the outer surface of each ear having a radius about said axissubstantially equal to one-half the length of one of said shorter walls.2. Apparatus according to claim 1 wherein said cutter further comprisesa stop member covering said aperture and situated intermediate the shearplate and coupling pin and wherein said drive end of the coupling pinhas a rounded terminal part which is urged axially into engagement withsaid stop member.
 3. Apparatus according to claim 1 wherein saidcoupling pin is tiltably mounted relative to said housing.
 4. Apparatusaccording to claim 1 wherein said coupling member is cylindrical with acentral bore, and said coupling pin is a separate element mounted foraxial movement in said bore and said spring means is situated in saidbore and urges said pin axially outward of the bore.
 5. Apparatusaccording to claim 1 wherein said coupling pin comprises sheet metal.